We've increased our level of making! Some explanation: we designed and 3D printed a tempeh mold, using food safe plastic (PETG), which we filled with half-ground soybeans and a fungus (rhizopus oligosporus) and let it grow in our custom-made incubator for ~30 hours. The result is this amazing, delicious, protein-packed tempeh <3

About plan files and tutorials: we document (almost) everything we do in our docs, and we're currently working on a common documentation to make everyone's life easier. Until that comes out, you can find our documentation here: Tempeh (, incubator - cabinet (, incubator - electronics (

"We" is actually Maud, my partner, and me. Our new collective is called Domingo Club :-) More info on this part very soon, but our goal is to make an incubator with open-source software/hardware that can be easily made in any fablab (network of shared digital fabrication workshops) to teach how to make fermented food, explore the possibilities of mycelium, and basically how to eat good food and feel good 🌄

@focus404 so pretty! will you be sharing the plan files? (now i’m curious !)

@mood As soon as we've made "official" our new collective (= set up our common doc on our new domain) 🌻

@focus404 really fantastic. I had no idea tempeh was fermented. TIL

@dualhammers I hope close to zero, which is why we chose PETG. But we don't have a way to measure/control this yet. I'll put this in our todo list, thanks!

@focus404 I am very curious about your plans regardless. I cannot eat soy so I am curious about other beans that could form tempeh. Maybe chickpeas?


Soy is just the first step for us as we moved last year to Barcelona, Spain, where organic and locally produced soy is almost impossible to find. The good news is that this country has delicious rice and you can make tempeh with it, and it is very yummy :-) We need more practice, but we are on it! Chickpea tempeh is also good, but a bit more technical to make.

@dualhammers I find it very complicated to take advantage of something that is not good for everyone. Organic preserves the soil, nature, wildlife, our planet.

@focus404 it really depends on what the person is doing that rhey define as "organic." For example some organic pesticides, like nicotine, are more carcinogenic than some non-organic pesticides. And depending on the crop they need more of them.

In the us much produce with the Organic label has to be shipped in from other countries, so the impact on wildlife is higher overall due to the added co2 from shipping.

@focus404 I do agree those priorities are the right one but I encourage you to do research to make sure the actual steps involve match your goals.

I may be saying things you have already heard, but choosing to build your tempeh device out of new plastics instead of, say, bamboo, has me wondering how deep you are investigating the impact.

@focus404 (i do not mean that as an insult, mind. I have done and often continue to do the same thing)

@dualhammers Don't worry, I don't take it as an insult but rather as a way to test an idea, which I appreciate. Thanks for your contribution ;-)

@dualhammers Yes, we are thinking deeply about the impact of adding more stuff around us. Two things to keep in mind for now: we're in the prototyping phase, which means the materials may not be the best, but at least they allow us and others to test/share/make/replicate our ideas and help us get closer to fermentation practices and to investigate new bio-materials; PETG is pretty easily recyclable and we have the tools to do so at Fab Lab Barcelona, thanks to the Precious Plastic project.

@kensanata @focus404 Nice! Does your process involve cooking the soybeans in the plastic mold to semi-sterilize it before innoculating with fungus? If so, what temp can that plasic handle? I think I would be tempted to make one that fits in an electric pressure cooker that has a yogurt function. e.g. cook at high temp, open & innoculate, seal back up and use yogurt setting. Would that work?

@resist1984 @kensanata Good point! For now, we cook the beans separately and wash the mold carefully with soap and water. No problems so far. The melting point of PETG is about 250°C (

@focus404 nice! gonna try that myself as well (already have the soy beans and fungus but need some warm place or incubator)

what brand of PETG is this? even though PETG itself is food safe it may contain additives which are not

@focus404 This is so nice. I would like to use this to form several pieces of soap that are too small to use into a new bar.

@focus404 Whoooaaa I might have to make a similar PETG mold, that looks amazing!

@somnius Hey, do you also make tempeh? I still have to upload the files but it's coming :-)

@focus404 I don't! I've had a friend make me some before, but haven't made any myself. I've been getting just a bit into cooking and drink making though!

@focus404 How do you keep your temperature just right? I've built a wooden box with a heating element and a thermostat to keep the temperature to set level. But never really got it right.

Maybe one could get a hold of that pattern and have it printed by those 3d printers at a service companies?

@sa0bse Is your temperature too high or too low? Fermented foods start to generate their own heat after about 15 hours, so that's something to consider. We plan to publish and document everything, I am just building our documentation system before we merge our two systems into one.

@focus404 I think it should be fine, let me share some pictures of the things I've experimented with last summer.

I have a plan to make a smaller box that may have some holes in the bottom and put the heating elements on the bottom. Then some holes at the top as well. And I will place the thermometer under the bags just to not overheat them from underneath.

I think my drying of the beans may not be good enough... But I found your link to your recipe in some other toot that I will study a bit:)

@sa0bse Hey, nice setup! From what I can see, it could be from different variables: Is your temperature high enough? Is your tempeh starter active enough or did you put enough in? And also/most importantly It's best to remove the hulls from the beans to help the fungus spread.

@focus404 how does it taste ? I mean, #tempeh in general. I am "vegan" and I never tried. 😋

@xavier I don't know how to describe the taste ... it's like ... tempeh? haha. What I can say is that I love it :-) Try it, you won't be disappointed.

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